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Query: UMLS:C0085631 (agitation)
 12,064 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of perfluorochemical (PFC) oxygen carriers in turkey semen diluents on fertility and hatchability was measured for a 10-wk period. Semen was diluted (1:1) with Beltsville Poultry Semen Extender (BPSE) or BPSE:FC-75, an emulsified mixture of BPSE and perfluorobutyltetrahydrofuran (technical grade) (FC-75) and stored for 24 h at 5 C with agitation (150 rpm) and aeration with either air, nitrogen (100%), or oxygen (100%). Sperm concentration and percentage of dead sperm were determined prior to and after storage. Sperm concentration (8.35 to 9.21 x 10(9) per milliliter) was not significantly affected by the type of diluent or aeration gas, and only stored semen diluted with BPSE: FC-75 and aerated with nitrogen had increased percentage of dead sperm. Diluent type did not affect the percentage of fertilized eggs; however, fertility and hatchability for both diluent treatments with nitrogen aeration was significantly lower (P < or = 0.05) than for the semen treatments with air or oxygen aeration. Hatchability for semen diluted with BPSE:FC-75 and aerated with oxygen (63.7%) was significantly higher (P < or = 0.05) than that for BPSE-diluted semen aerated with oxygen (43.2%). Although use of oxygen carrying fluorocarbon emulsified with BPSE did not further improve fertility when the semen was stored for 24 h while oxygenated and mechanically agitated, a beneficial effect was noted for hatchability. The fact that nitrogen severely depressed fertility confirms that the beneficial effects of agitation are due to oxygenation of the spermatozoa. Therefore, further studies of oxygen carriers in semen are warranted.
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PMID:Effects of varying aeration treatment on fertilizing capacity of semen diluted with perfluorochemical emulsion and stored for twenty-four hours. 965 19

It has been found previously that a significant number of Micrococcus luteus cells starved in a prolonged stationary phase (up to 2 months) and then held on the bench at room temperature without agitation for periods of up to a further 2-7 months can be resuscitated in liquid media which contained (statistically) no initially-viable (colony-forming) cells but which were fortified with sterile supernatant from the late logarithmic phase of batch growth. Here it was found that such resuscitation can be done only within a defined time period after taking the first sample from such cultures, necessarily involving agitation of the cells. The duration of this period depends on the age of the starved culture: cells kept on the bench for 3 months possess a 2 month period of resuscitability while cells starved for 6 months can be resuscitated only within 10 days after the beginning of sampling. It is suggested that the input of oxygen to the starved cultures while they are agitated may exert a negative influence on the cells, since cultures stored in anaerobic conditions (under nitrogen) had a more prolonged 'survival' time. The cells which experienced between 10 and 60 days of starvation on the bench could be resuscitated, although the number of resuscitable cells depended strongly on the concentration of yeast extract in the resuscitation medium. This concentration for cells stored on the bench for more than 2 months was 0.05% while '1-month-old' cells displayed a maximum resuscitability in the presence of 0.01% of yeast extract. Application of the fluorescent probe propidium iodide revealed the formation of cells with a damaged permeability barrier if resuscitation was performed by using concentrations of yeast extract of 0.1% and above. Thus the successful resuscitation of bacterial cultures under laboratory conditions may need rather strictly defined parameters if it is to be successfully performed for the majority of cells in a population.
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PMID:On resuscitation from the dormant state of Micrococcus luteus. 980 68

The growth and metabolic behaviour of the filamentous fungus Monascus ruber were studied in submerged cultures under various aeration and agitation conditions. Improving the oxygen supply, by increasing either the air input or the agitation speed, resulted in modified metabolism: the biomass yield, the consumption of the nitrogen source (monosodium glutamate), and the production of secondary metabolites (red pigment and citrinin) all increased. However, the citrinin production increased more than that of the red pigment. In consequence, a low oxygen transfer coefficient was required to improve the red pigment/citrinin production ratio. Copyright 1999 John Wiley & Sons, Inc.
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PMID:Improvement of red pigment/citrinin production ratio as a function of environmental conditions by monascus ruber 1039 88

Succinoglycan was produced by cultivating Agrobacterium tumefaciens on various solid substrates, including agar medium, spent malt grains, ivory nut shavings, and grated carrots, impregnated with a nutrient+ solution. Fermentations were performed on a laboratory scale, both under static conditions and with agitation, using bottles and a prototype horizontal bioreactor. Several fermentation parameters were examined and optimized, including carbon and nitrogen composition, water content and layer thickness of the substrate. The yields and rheological properties of the polymers obtained under different fermentation conditions were compared. The highest succinoglycan yield was achieved in static cultivation, reaching 42 g/l of impregnating solution, corresponding to 30 g/kg of wet substrate. The polymer production in the horizontal bioreactor was faster, but the final yield was lower (29 g/l of impregnating solution).
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PMID:Succinoglycan production by solid-state fermentation with Agrobacterium tumefaciens. 1053 45

Bacteriocins produced by lactic acid bacteria are a heterogeneous group of peptide inhibitors which include lantibiotics (class I, e.g. nisin), small heat-stable peptides (class II, e.g. pediocin AcH/PA1) and large heat-labile proteins (class III, e.g. helveticin J). Many bacteriocins belonging to the first two groups can be successfully used to inhibit undesirable microorganisms in foods, but only nisin is produced industrially and is licensed for use as a food preservative in a partially purified form. This review focuses on the production and purification of class I and class II bacteriocins from lactic acid bacteria. Bacteriocin production is growth associated but the yield of bacteriocin per unit biomass is affected by several factors, including the producing strain, media (carbohydrate and nitrogen sources, cations, etc.) and fermentation conditions (pH, temperature, agitation, aeration and dilution rate in continuous fermentations). Continuous fermentation processes with cell recycle or immobilized cells can result in a dramatic improvement in productivity over batch fermentations. Several simple recovery processes, based on adsorbing bacteriocin on resins or silica compounds, have been developed and can be used to build integrated production processes.
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PMID:Production, recovery and purification of bacteriocins from lactic acid bacteria. 1057 Aug 9

The purpose of this study was to evaluate the effect of pH on the extraction of protein nitrogen from Atriplex lampa leaves (Moquin) Dietrich. The chemical characterization of the dry matter indicated the following (g/100 g): protein, 26.93; ash, 21.80; ether extract, 4.65; dry matter, 37.30; sodium, 6.05; and calcium, 0.41. Non-critical values were obtained for saponins and nitrates. The high concentration of oxalic acid (8.52 g/100 g), together with elevated salt content account for the low palatability of the studied species. In order to determine the parameters needed to improve the extraction in protein nitrogen from leaves, fresh material was macerated with 2% sodium metasulfite, followed by pulping with a hand-driven grinder. Extractions were performed at different pH values (2-12) adjusting the value with 5N HCL or NaOH, with agitation followed by centrifugation and pressing. Supernatants were collected and kept. The last extraction was performed with Tween 20 in order to obtain maximum nitrogen recovery from the residue cake. Highest extraction (41.23%) was obtained at pH 10 with a 1:5 ratio (leaf: deionized water, w/v). It is proposed that this regional natural resource may be used to elaborate a protein concentrate, which can be made more palatable by decreasing potassium and sodium salt content with the use of membrane technology.
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PMID:Protein extraction from Atriplex lampa leaves: potential use as forage for animals used for human diets. 1071 6

Production of the extracellular heme protein lignin peroxidase (LiP) by Phanerochaete chrysosporium is currently associated with a number of requirements, namely exposure of the cultures to oxygen; limiting nutrient nitrogen or carbon and static or semi-static culture conditions. To obtain LiP activity in continuously agitated liquid culture requires the inclusion of a surfactant. However, using cellulose as the carbon source, we obtained high titres (0.2-0.4 U ml(-1)) of LiP in submerged liquid cultures under conditions of continuous agitation, without substrate limitation or the need to add oxygen or surfactant. Comparison of the morphological and physiological traits of hyphae maintained on either cellulose or free glucose supports observations that the synthesis of extracellular polysaccharide in the cultures grown on glucose, restricts oxygen diffusion into the hyphae, which is necessary for LiP induction. They also suggest that isozymes of LiP synthesised under these conditions may be triggered in response to oxidant stress.
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PMID:Metabolism of cellulose by Phanerochaete chrysosporium in continuously agitated culture is associated with enhanced production of lignin peroxidase. 1072 41

Increasing glycerol production is of concern for wine-makers in improving the quality of certain wines. We have compared the impact of strain and relevant environmental factors influencing glycerol production under the same conditions, i.e. standardized conditions simulating enological fermentation. The glycerol production of 19 industrial wine strains ranged from 6.4 to 8.9 g l-1 and varied significantly between strains. The production of acetate and succinate was also found to differ substantially depending on the strain but no significant strain-dependent variation was observed for acetaldehyde. Interestingly, high glycerol production was not correlated to high production of acetate or acetaldehyde, which are undesirable in wine. A detailed study with two low or two high glycerol-producing strains showed that temperature and the initial concentration of nitrogen had little effect on the amount of glycerol formed, although agitation or a nitrogen source composed mainly of ammoniacal nitrogen slightly enhanced glycerol production. The influence of environmental factors remained minor while the predominant factor for glycerol variability in wine was attributed to the strain. Taking into account wine-making constraints, the results indicate that achieving a high glycerol content in wine requires the selection or improvement of yeast strains rather than the control of growth and cultivation conditions.
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PMID:Re-assessment of the influence of yeast strain and environmental factors on glycerol production in wine. 1074 17

The role played by a bacterial community composed of Pseudomonas putida, strain 21, Pseudomonas stutzeri, strain 18, and Pseudomonas sp., strain 5, and by physical and chemical factors in the degradation of CN- and SCN- was studied. It was shown that the degradation of CN- is determined both by the action of bacteria and by abiotic physical and chemical factors (pH, O2, temperature, the medium agitation rate, etc.). The contribution of chemical degradation was found to increase drastically at pH below 9.0; when air was blown through the medium (irrespective of the pH value); under active agitation of the medium; and when the medium surface interfacing air was increased. Even at elevated pH values (9.0-9.2), suboptimal for bacterial growth, the microbial degradation could account for at most 20-25 mg/l of CN-, regardless of its initial concentration. When CN- and SCN- were concurrently present in the medium, the former compound was the first to be degraded by microorganisms. The rate of bacterial degradation of SCN- under continuous cultivation in a chain of reactors was found to depend on its concentration, the medium flow rate, agitation rate, and the pattern of carbon source supply and could exceed 1 g/(1 day). CN- and SCN- are utilized by bacteria solely as nitrogen sources. The mechanism of CN- and SCN- degradation by the microbial community is discussed.
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PMID:[Microbial destruction of cyanide and thiocyanate]. 1077 20

Restless is an endogenous hAT transposon found in the cyclosporin-producing fungus Tolypocladium inflatum. This element is present in about 15 copies in a particular strain (ATCC34921) which was used for successful gene tagging. We have isolated a T. inflatum mutant with a defect in nitrogen metabolism. This mutant carries a copy of the Restless element in a gene encoding a C6 zinc-finger protein. The deduced amino acid sequence of the gene product shows a significant similarity to the NIT4 protein of Neurospora crassa, which is a regulator of nitrogen metabolism. The wild-type T. inflatum gene was shown to complement a nit-4 mutant of N. crassa. From these data, we conclude that the T. inflatum gene also encodes a regulator of nitrogen metabolism, which was named tnir1 (Tolypocladium nitrogen regulator 1). To the best of our knowledge, this is the first fungal gene to be identified by transposon-directed gene tagging. A general method for gene tagging using an endogenous fungal transposon is presented.
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PMID:Tagging of a nitrogen pathway-specific regulator gene in Tolypocladium inflatum by the transposon Restless. 1077 49


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